Starting connection for alternating currents



DEC. 22, 1931. E, MAYER 1,837,563

I STARTING CONNECTION FOR ALTERNATING CURRENTS Original Filed Jan. 9,1924 la-l IHVENTOR Emil "lag r HTTORH Y.

Patented Dec. 22, 1931 UNITED STATES PATENT OFFICE EMIL MAYER, OFSCHENECTADY, NEW YORK STARTING CONNECTION FOR ALTERNATING CURRENTS Thisapplication is a division of application U. S. Serial No. 685,212, filedon January 9, 1924, now Patent N 0. 1,678,897, June 12, 1928.

My invention relates to improvements in starting apparatus for electricmotors, particularly alternating current motors having either wound orunwound rotors.

An obJect of my invention is to provide a starting arrangement foralternating current motors using electrical condensers either alone orin combination with resistances; with the result that I can obtainlarger torque with smaller starting currents, because the condensersinfluence the phase of the starting current more strongly than aresistance; and thus with a given current, a larger torque can bedeveloped.

A further object of my invention is to provide a method of startingalternating current motors adapted to permit the phase-compensationcondensers employed with alternating current motors of this and othertypes, to be utilized for purposes of starting; and after starting to berestored to their proper relations in the circuit to function asphase-compensation condensers for the regular operation of such motors.

Other objects and advantages of the invention will appear from thefollowing description, which shows connections and circuits according tomy invention, but it is to be understood, however, that this disclosureis illustrative only and I do not wish to be necessarily limited to whatis described, or shown upon the drawings, and I reserve the rightto makeany changes which come within the scope and spirit of the invention asthe same are indicated in the appended claims.

On the drawings, Fig. 1 is a diagrammatic view showing the connections.for starting an alternating current motor having an unwound rotor;

Fig. 2 shows such connections for normal running;

Fig. 3 is a view showing the same conditions as Fig. l, with switchterminals for changing the connections from starting to running,included; and,

Fig. 4 is a'view similar to Fig. 2 showing Germany October 31, 1923.Divided No. 268,066.

the connections altered to establish regular running conditions.

In the drawings, the invention is illustrated in connection withalternating currents of three phases, but obviously, I may practice theinvention with motors taking current of a different number of phases;and, in fact, with alternating current motors in general, after themanner set forth in the actual embodiment of my invention which is herere resented for purposes of explanation.

eferring first to Fig. 1, I show a three phase alternating arrangementin which the operating current is taken from the-main leads, 1, 2 and 3.The motor windings are indicated at wl, 1/02, and 'w3 respectively, andhaving its opposite extremity connected to a common terminal of thethree windings; so that these windings are joined in the socalled staror Y connection.

ndensers are indicated at c, unitedto the terminals of the threewindings 110, 2/10, and 3w, which are joined to the main supply wires,that is, each of the condensers will be bridged across two of thewindings of the motor, so that while the motor windings are in Yconnection, the condensers themselves will be connected in delta. Thewindings are, of course, the field windings, and in connection with Fig.1, it is to be remembered that the motor is to have an unwound rotor,for example, a rotor of the squirrel cage yp Such a motor can be startedwith connections as shown in Fig. 1, but after starting, and for normalrunning the windings and condensers must be placed in the relationsshown in Fig. 2. This view shows the three windings connected in delta,and the three condensers connected in star or Y, for the motor tooperate in the usual way, under normal conditions. With the connectionsshown in Figs. 1 and 2, the usual resistances are either not required,or smaller resistances than usual can be employed. Also the startingperiod is short, and during thatperiod the aggregate condenser capacitycan be subjected to greater stress without danger; and to that end thecondensers can be so connected that they possess a greater'aggregatecapacity at starting; and thereby the object of the inclusion of thecondensers can be gained with a smaller and cheaper condenserconstruction.

In Figs. 3 and 4, I show means whereby the connections can be changedfrom the arrangement utilized for startin as indicated in Fig. 1, tothat utilized for regular operation, indicated in Fig. 2.

In Fig. 3, the three windings, e01, 102 and 103, are each united at oneend to one of the main leads, and the opposite extremity of the threewindings are each joined to separate, switch terminals, 1m, 2m and 3m.These three terminals are all connected together to put the three motorwindings in Y or star.

In the line of the conductors, 1w, 2w and 3w, are other switch terminalsml, m2 and m3, each being opposite one of the switch terminals justmentioned. Thus the winding 101, for instance, will have one end joinedto the swi eh terminal 1m, and the opposite extremity joined to theterminal ml, which is connected to the lead 1, and so with the other twowindings.

The condensers are shown at S, and each condenser will have its oppositeextremities connected to a pair of switch terminals, the same as themotor windings. A conductor will run from the switch terminal ml to aterminal 01, to which one pole of one of the condensers is joined, andopposite this terminal 01 is another terminal 10, united to the otherpole of the condenser. Two more opposite switch terminals, 02 and 2c andc3 and 30 for the other two condensers, will be provided; and theterminal 02 will be joined to the wire 2w, and the terminal 03 to thewire 3w, the two condensers for these extra two pairs of switchterminals being joined thereto in the same way as the first condenser.With the terminals, 1m, 2m, and 3m all joined together, as indicated bythe straight line, and the switch terminal 01 connected to switchterminal 20, switch terminal 02 to switch terminal 30, and switchterminal 10 to terminal 03, it will be apparent that with the windingsin star, the con densers will be in delta, as Fig. 1 shows them. Themotor can then be started with these connections; the relation in whichthe switch terminals are united being indicated by the broken lines inFig. 3. For running, the connections are changed between the three setsof the motor winding terminals and the three pairs of condenserterminals to put the con densers in star and the windings in delta; themanner in which the various switch terminals are now joined beingindicated in Fig. 4; a single straight line being employed to unite theterminals 10,20 and 30, to show the three condensers with one poleunited to a single point and broken lines to indicate the manner ofjoining up in the proper way, the terminals for the windings ad, 102 andtroller.

@113. Fig. 4, in other words, shows the windings connected the same asthe condensers are connected in Fig. 3. switch may be utilized toconnect the switch terminals, as indicated in Fig. 3 and then asindicated in Fig. 4. For this purpose, the switch terminals that I havedescribed may be mounted so as to be fixed or stationary and may work incombination with a rotatable member designed to connect them asrequired, after the fashion of a rotary con- I do not describe such acontroller fully here as my invention is concerned more with the broadidea of making the connections for starting and normal operation in themanner set forth, and not particularly with any especial switchingdevices which may be useful for my purpose.

Having described my invention what I believe to be new and desire tosecure and protect by Letters Patent of the United States 1. The methodof operating alternating current motors which comprises connectingcondensers in delta and to the motor windings during starting andconnecting the condensers in star connection for running.

2. The method of operating alternating current motors which comprisesconnecting during starting, the motor windings in star and condensers indelta and in shunt with the windings and during operation connect ingthe motor windings in delta and the condensers in star and in shunt withthe windings.

In testimony whereof I have aiiixed my signature.

EMIL MAYER.

Obviously, a single

